I have build a system where 2 parties in conference can perform certain functions via DTMF tones while in conversation with each other. I have picked up that randomly during the day certain DTMF digits are not processed via AGI. On closer inspection I found that the DTMF digits are processed by the pbx but never gets to the AGI part.After close scrutiny it became apparent that the digits not reaching AGI are those with the following field (in bold) somehow changed. My question is what is this field and why did it change?